We had something similar happen with Nephew's Daughter when they visited a few years ago. We went out to a Middle Eastern place and the 5 year-old little girl ordered fries with her falafel and salad The waiter brought two squeeze bottles of sauce. One was white (tahini) and the other was red (Harissa). Thinking the red bottle was the ketchup she was used to using, the little girl liberally slathered it on her fries while the adults were chatting.
Oh, the response! It was a good thing that many of the adults who ordered fries liked spicy food. It was easy to transfer untainted fries to the little girl's plate and secure her some proper ketchup.
There must have been other problems of this nature because the restaurant now puts a white squeeze bottle of tahini and a glass bottle of hot sauce on the table.